A recent study suggests that thousands of people in the UK are likely to be the result of “extreme inbreeding” between close relatives.
In-Depth scrutiny of DNA stored in the UK Biobank, which stores hundreds of thousands of volunteers’ genetic matter, found that a fraction of those sequenced was conceived by parents who are either first or second-degree relatives. A first-degree relative is a person who shares 50 % of a person’s genes like a parent or child, while a second-degree relative is someone who shares 25 %of the same DNA and covers uncles, grandparents, and half-siblings.
Out of a total of more than 450,000 participants, researchers from the University of Queensland found 125 cases whose genes suggested that they were the offspring of extreme inbreeding. All volunteers were individuals of European descent born between 1938 and 1967.
Extrapolating this sample data across England and Wales resulted in an estimate of 13,200 people born to inbreeding, but the study’s authors caution that the figure could be even higher.
The researchers said in a statement to the Daily Mail, “The extent to which our estimate reflects the true prevalence of [extreme inbreeding] in the entire UK population is a difficult question. The UK Biobank is known to have over-representation from healthy and highly educated individuals, which likely biases our estimates. Highly inbred individuals who suffer severe health consequences may be less likely to participate in a study such as the UK Biobank. Therefore, our estimate of the prevalence might be too low.”
The DNA study was led by Dr. Loic Yengo and published recently in Nature Communications. It summaries the many health consequences for children born to incest such as increased chances of low fertility, stunted growth and lifespan, poor lung function and reduced cognitive ability. To identify whether an individual was conceived through inbreeding or not, the researchers looked for abnormally high incidences of DNA sections identical to each other termed as homozygosity.
As per the American College of Medical Genetics, DNA which features 10% or more homozygosity is assumed to be the result of the same genetic code being inherited from the mother and father.